Résumé : Une dysrégulation de la lipolyse des tissus adipeux peut conduire à une surexposition des tissus non-adipeux aux acides gras non-estérifiés (AGNE), qui peut mener à un certain degré de lipotoxicité dans ces tissus. La lipotoxicité constitue, par ailleurs, l’une des causes majeures du développement de la résistance à l’insuline et du diabète de type 2. En plus de ses fonctions glucorégulatrices, l’insuline a pour fonction d’inhiber la lipolyse et donc de diminuer les niveaux d’AGNE en circulation, prévenant ainsi la lipotoxicité. Il n’y a pas d’étalon d’or pour mesurer la sensibilité de la lipolyse à l’insuline. Le clamp euglycémique hyperinsulinémique constitue la méthode étalon d’or pour évaluer la sensibilité du glucose à l’insuline mais il est aussi utilisé pour mesurer la suppression de la lipolyse par l’insuline. Par contre, cette méthode est couteuse et laborieuse, et ne peut pas s’appliquer à de grandes populations. Il existe aussi des indices pour estimer la fonction antilipolytique de l’insuline dérivés de l’hyperglycémie provoquée par voie orale (HGPO), un test moins dispendieux et plus simple à effectuer à grande échelle. Cette étude vise donc à : 1) Étudier la relation entre les indices de suppressibilité des AGNE par l’insuline dérivés du clamp et ceux dérivés de l’HGPO; et 2) Déterminer laquelle de ces mesures corrèle le mieux avec les facteurs connus comme étant reliés à la dysfonction adipeuse : paramètres anthropométriques et indices de dysfonction métabolique. Les résultats montrent que dans le groupe de sujets étudiés (n=29 femmes, 15 témoins saines et 14 femmes avec résistance à l’insuline car atteintes du syndrome des ovaires polykystiques), certains indices de sensibilité à l’insuline pour la lipolyse dérivés de l’HGPO corrèlent bien avec ceux dérivés du clamp euglycémique hyperinsulinémique. Parmi ces indices, celui qui corrèle le mieux avec les indices du clamp et les paramètres anthropométriques et de dysfonction adipeuse est le T50[indice inférieur AGNE] (temps nécessaire pour diminuer de 50% le taux de base – à jeun – des AGNE). Nos résultats suggèrent donc que l’HGPO, facile à réaliser, peut être utilisée pour évaluer la sensibilité de la lipolyse à l’insuline. Nous pensons que la lipo-résistance à l’insuline peut être facilement quantifiée en clinique humaine. / Abstract : It has been shown that a dysfunctional regulation of adipose-tissue lipolysis could conduct to non-adipose tissues overexpos ure to non exterified fatty acids (NEFA), leading to lipotoxicity. Lipotoxicity is considered as a key factor in the development of insulin resistance and type 2 diabetes. Insulin regulates glucose metabolism but also NEFA storage and release. To our knowledge, there is no gold standard for evaluating insulin sensitivity for lipolysis. The gold standard to measure insulin sensitivity for glucose is the euglycemic-hyperinsulinemic clamp. This method is simple to interpret because it achieves static levels of metabolic parameters at the end of each step of the clamp. The major limit of the clamp is that it is time-consuming, expensive and cannot be used on large population. On the other hand, the oral glucose tolerance test (OGTT) consists in a dynamic test also used to estimate insulin mediated glucose disappearance after ingestion of 75 g of glucose. Since the OGTT is easier to use, less expensive and can be suggested in large cohort studies, its potential use has been suggested to estimate insulin sensitivity for lipolysis, as well. T his work is the first to validate the use of simple indices derived from OGTT to estimate insulin sensitivity for lipolysis against the euglycemic clamp and adipose-tissue dysfunction in women. The results of this study clearly show in a group of 29 women (15 normal and 14 with polycystic ovary syndrome, who are used to increase the range of insulin resistance) that T50[subscript NEFA] (time to suppress 50% of NEFA baseline levels) during OGTT is the best index associated with glucose insulin clamp indices and clinical markers related to adipose tissue dysfunction and metabolic parameters. T50[subscript NEFA] (OGTT) was also better associated with central adiposity and metabolic parameters than clamp-derived indices. Since the OGTT is much easier to perform and is less expensive than the clamp technique, the use of OGTT to calculate T50[subscript NEFA] seems to be a valid method to assess antilipolytic action of insulin in large cohorts.

L'insulino-résistance est une caractéristique majeure du syndrome métabolique dont l'incidence ne cesse d'augmenter dans les pays industrialisés parallèlement à l'épidémie d'obésité. La résistance à l'insuline s'accompagne de diverses atteintes au niveau cardiaque, vasculaire et rénal. L'objectif principal était dans un modèle d'insulino-résistance induite par un excès de fructose chez le rat d'évaluer l'influence de la modulation en sodium (en excès ou en restriction) sur les changements métaboliques cardio-rénaux. D'une part, l'influence d'une restriction sodée concomitante à un régime riche en fructose a été évaluée. Nous avons montré que la restriction sodée prévenait les dommages cardio-rénaux. Ces effets bénéfiques ont été associés à une diminution de l'inflammation rénale et du stress oxydant. De plus, une prévention des modifications du tissu adipeux induites par le régime riche en fructose a été également observée. D'autre part l'impact d'une insulino-résistance en présence d'une consommation excessive et précoce (sevrage) en sodium a été évalué. Quand l'insulino-résistance (régime fructose) est initiée secondairement à un régime hypersodé, l'hypertrophie cardiaque associée au régime sodé est diminuée après l'ajout d'une insulino-résistance. Ce résultat paradoxal pourrait représenter une mal-adaptation du muscle cardiaque que confirme l'altération de la fonction systolique. En conclusion ce travail démontre une fois de plus l'impact de la nutrition dans la modulation des atteintes des organes cibles. L'importance d'adopter une nutrition raisonnée par contrôle de l'ingestion de sodium peut permettre de réduire les atteintes des organes cibles observées dans l'insulino-résistance. / Insulin resistance is a major feature of the metabolic syndrome whose incidence is increasing in industrialized countries, in parallel with the obesity epidemic. Insulin resistance is associated with various cardiac, vascular and renal damages. The main objective was to evaluate the influence of sodium modulation (excess or restriction) on cardio-renal changes in a model of insulin resistance induced by fructose in rats. On one hand, the influence of salt restriction concomitant with a high fructose diet was evaluated. We have shown that sodium restriction prevents cardio-renal damages. These beneficial effects were associated with a reduction in renal inflammation and oxidative stress. In addition, a prevention of adipose tissue changes induced by fructose-rich diet was also obeserved. On the other hand impact of insulin resistance in presence of an early (weaning) sodium and excessive consumption of sodium was evaluated. When insulin resistance (fructose diet) was initiated secondary to high salt diet, cardiac hypertrophy associated with sodium diet decreased after the addition of insulin resistance. This paradoxal result could represent a maladaptation of cardiac muscle confirmed the impaired systolic function. In conclusion this work further demonstrates the impact of nutrition in the modulation of target organ damage. Reducing sodium intake may provide an easy way to reduce target organ damage observed in insulino resistance.

Obesity is widely considered a primary risk factor for type 2 diabetes (T2D). However, less is known about the early adaptive responses to short-term periods of high-fat energy excess (HFEE). Previous reports detailing whole-body adaptation to fat and energy oversupply are equivocal, perhaps, in part, owing to use of different experimental protocols, varying durations of dietary manipulation and participant cohorts with individuals of varying characteristics. In addition to use of different dietary protocols between studies, alterations in functional end-point measures due to the type of dietary fat consumed warrants consideration. Daily n-3 PUFA intake, commonly obtained from pelagic fish oil (FO) consumption, has been shown to positively associate with insulin sensitivity in epidemiological studies and thus may be a useful dietary strategy for slowing insulin resistance development. Chapter 2 of this thesis extends previous literature by demonstrating that 6 d HFEE (150 % habitual energy intake; 60 % of energy from fat) does not clearly alter whole- body insulin sensitivity, irrespective of FO consumption. However, investigation of metabolism at the tissue level, as presented in Chapter 3 of this thesis, offers insight into a potential tissue-specific level of regulation that precedes whole-body regulation. Skeletal muscle insulin signalling protein (e.g. protein kinase B (PKB)) activity, levels of certain ceramide species, and AMPK α2 activity were altered following HFEE and may explain the early maladaptive responses to short-term HFEE. Moreover, FO intake as 10 % of total fats mediated some of these molecular responses, including PKB and AMPK α2 activity, reflecting possible functional effects of FO at the subcellular level. Regulation of these metabolic / molecular responses at both the tissue and whole- body level can be explained, in part, by genetic predisposition, environmental influence and more recently epigenetics, including microRNAs (miRNAs). In Chapter 4, we characterised the plasma and skeletal muscle miRNA responses to HFEE and oral glucose ingestion. We demonstrate transient changes in levels of certain miRNAs following oral glucose ingestion in both tissue types and in response to HFEE in skeletal muscle. However, no significant correlations between basal plasma and skeletal muscle miRNA levels were observed, suggesting that our candidate plasma miRNAs may be co-ordinating functional changes in other tissue types. Plasma miR- 145-5p and skeletal muscle miR-204-5p predicted a significant proportion of the variance in mean whole-body insulin sensitivity change in response to HFEE. These data indicate that these miRNAs may be useful biomarkers of insulin resistance development following HFEE. A constraint of this thesis is that all conclusions are made within the context of statistically unaltered insulin sensitivity. Therefore, future investigations of diet-induced maladaptation should consider establishing a time course of insulin resistance development in response to HFEE, or use different study populations. Populations that are more susceptible to T2D development, e.g., overweight, sedentary individuals would be of particular interest. These data would aid development of a working model of diet-induced insulin resistance that has more direct application to T2D progression and extends the data presented herein.

Le système endocannabinoïde (SEC) est un système clé de la régulation de la balance énergétique. Les rares études réalisées chez l’Homme concluent à une augmentation des concentrations plasmatiques des endocannabinoïdes, anandamide (AEA) et 2-arachidonoylglycerol (2-AG), chez les sujets obèses ou diabétiques de type 2. Cependant plusieurs questions restent posées et cette thèse s’est spécifiquement intéressée : i) à l’existence d’une cinétique prandiale et au rôle des endocannabinoïdes circulants par rapport à la prise alimentaire, ii) aux effets d’une perte de poids obtenue par court-circuit gastrique sur ces concentrations et iii) aux liens physiopathologiques entre insulinorésistance et SEC. Enfin, nous avons tenté de développer un outil non invasif pour faciliter l’étude du SEC chez l’Homme. Dans la 1ère étude, nous avons mis en évidence pour la première fois une augmentation préprandiale de l’AEA indépendante du poids. Ceci suggère que l’AEA plasmatique pourrait jouer un rôle dans l’initiation de la prise alimentaire chez l’Homme. De façon intéressante, la réduction post prandiale de l’AEA est émoussée chez les sujets obèses insulinorésistants, ce qui peut créer un cercle vicieux vis à vis de l’obésité. Dans la 2ème étude, des résultats préliminaires montrent qu’une même perte de poids obtenue par court-circuit gastrique ou par règles hygiéno-diététiques modifie différemment les concentrations plasmatiques d’AEA qui tendent à augmenter après court-circuit gastrique alors qu’elles ne sont pas modifiées après règles hygiéno-diététiques. Ainsi, le court-circuit gastrique pourrait directement affecter le fonctionnement du SEC localisé au niveau du tractus gastro-intestinal. Dans la 3ème étude, 72 heures de régime hypoglucidique permettent de diminuer significativement la glycémie à jeun et la résistance à l’insuline de 8 sujets diabétiques de type 2, mais pas les concentrations plasmatiques d’endocannabinoïdes, qui ne sont par ailleurs pas modifiées chez ces sujets en fonction du statut nutritionnel. Enfin, nous avons pu déterminer les concentrations des endocannabinoïdes dans la salive humaine, qui sont plus élevées chez les sujets obèses par rapport aux normopondéraux, avec une diminution de l’AEA salivaire associée à la perte de poids, mais sans variation en fonction de la prise alimentaire. La salive pourrait donc constituer un outil non invasif pour l’étude du SEC chez l’Homme.Ainsi, notre travail confirme les liens entre SEC et pathologies métaboliques chez l’Homme. Nos résultats suggèrent en particulier un rôle physiologique de l’AEA dans la prise alimentaire ainsi que l’importance potentielle du SEC du tractus gastro-intestinal. Nous confirmons la dérégulation statique et dynamique du SEC dans la situation de diabète de type 2. Enfin nous développons un nouvel outil pour l’exploration du SEC chez l’Homme. Nos résultats sont importants car la meilleure connaissance des systèmes impliqués dans la régulation de la balance énergétique est nécessaire pour le développement de nouvelles stratégies thérapeutiques efficaces contre l’obésité et ses pathologies associées. / The endocannabinoid system (ECS) is a key system for the regulation of energy balance. Only few studies have been so far carried out in humans but they all lead to conclude that obese subjects have higher plasma fasting levels of the 2 major endocannabinoids, anandamide (AEA) and 2-arachidonoylglycerol (2-AG). However, many questions concerning the role of the ECS in the physiopathology of obesity in humans remain still unanswered. This thesis has therefore attempted to address some of these questions by investigating i) the changes of plasma endocannabinoids in response to food intake, ii) the effect of weight loss induced by gastric bypass or lifestyle intervention on these plasma levels and iii) the potential link between insulin resistance and circulating endocannabinoids. Lastly, we have also tested the possibility to develop a non-invasive tool to ease the investigation of the ECS in humans. In the 1st study, we have described for the first time the existence of a pre-prandial peak in plasma AEA, which is independent of body weight. This evidence suggests that circulating AEA levels might work as a meal initiator factor in humans. Importantly, the AEA postprandial decrease is blunted in obese insulin resistant subjects and might therefore favor the persistence of the obese phenotype. In our 2nd study, preliminary results suggest that the same body weight loss obtained through gastric-bypass or lifestyle intervention differently affects plasma AEA levels. In particular, while AEA tend to increase in subjects who have undergone gastric bypass, no changes are observed after a comparable weight loss induced by lifestyle intervention. Thus, a possibility is that the bypass might directly affect the function of the ECS localized within the gastrointestinal tract. In our 3rd study, which was carried out on 8 type 2 diabetic patients, we have shown that 72 hours of a low carbohydrate diet significantly decreases glycaemia and insulin resistance, without affecting the levels and the kinetic of circulating endocannabinoids. Lastly, we demonstrated that endocannabinoids are reliably measured in saliva. Salivary endocannabinoids are higher in obese as compared to normal weight subjects. Body weight loss significantly decreases salivary AEA, while the consumption of a meal does not influence salivary endocannabinoids levels. Altogether our studies confirm the association between ECS deregulation and metabolic disease in humans. In particular, we have demonstrated that plasma AEA might have a physiological role in the regulation of human feeding behavior, and have hinted the potential relevance of the gastro-intestinal ECS in our studies on gastric-bypass patients. We have also shown that in type 2 diabetes, there is a flattening of the kinetics of circulating endocannabinoids. Finally, we have shown that measurement of salivary endocannabinoids is reliable and might be of clinical value. These findings extend our knowledge on one of the systems majorly implicated in energy balance regulation. Such knowledge is a necessary step towards the development of novel therapeutic strategies needed to halt obesity and metabolic disease.

Identifying the relationship between fat oxidation and insulin resistance (IR) may provide vital clues to the mechanisms behind the development of metabolic disease in prepubertal children. The purpose of this study was to examine the association of fat oxidation with insulin resistance (IR) and insulin sensitivity (SI) in prepubertal children. A total of 34 prepubertal 7-9 year olds (18 females, 16 males, 13 non-Caucasian, 21 Caucasian, 8.0±0.8 years, 36.5±12.1 kg) were observed. Subjects participated in indirect calorimetry to obtain respiratory quotient (RQ) and a blood test to obtain fasting insulin and glucose to calculate IR by homeostatic model assessment (HOMA). A subset (n=16) participated in Frequently Sampled Intravenous Glucose Tolerance Testing (FSIGTT) to obtain insulin sensitivity. Pearson correlations between RQ and IR and RQ and SI were performed. Partial correlations with respect to physical activity, breastfeeding, and birth weight were also performed. A general linear model was used to examine RQ with IR, and separately SI with respect to physical activity, breastfeeding, birth weight, race and sex. Respiratory quotient and IR were significantly associated when adjusted for physical activity, sex and race and breastfeeding, sex and race. In regards to birth weight, RQ and IR were significantly associated when adjusted for breastfeeding, birth weight, and race, but not when breastfeeding was removed from the model. The results of this study suggest lack of physical activity and breastfeeding may be the most influential risk for factors in the development of IR via a mechanism of impaired fat oxidation. Further research is needed to examine the role of physical activity, breastfeeding, and birth weight on fat oxidation and the development of insulin resistance in prepubertal children, however, the results of this study support the promotion of physical activity, breastfeeding, and good maternal nutrition.

O balanço energético corporal é mantido através de alterações na ingestão de calorias e no gasto energético. O prolongado balanço energético positivo, em que a ingestão excede o gasto, promove obesidade. A obesidade resulta do aumento de triacilglicerois no tecido adiposo, que também passa a apresentar inflamação de baixo grau crônica. O resultado disso envolve a redução da capacidade de tamponamento dos ácidos graxos livres circulantes e subsequente deposição de gordura em territórios ectópicos como musculatura esquelética e fígado, além de aumentar o risco de desenvolver o diabetes Mellitus tipo 2. Assim, a obesidade é um fator de risco importante para doenças metabólicas e suas comorbidades, dentre elas a doença gordurosa hepática não alcoólica. Uma proposta terapêutica para intervir na obesidade e/ou nas comorbidades associadas é o uso de substancias com ação anti-inflamatória. Considerando a possibilidade de novo uso para alguns produtos liberados para uso e com potencial tóxico já avaliado, foi escolhido avaliar o efeito do fitoterápico Uncaria tomentosa. Para isso, foram utilizados dois modelos de camundongos: (1) obesidade induzida por dieta hiperlipídica (DH), camundongos machos c57bl/6, alimentado com DH por 10 semanas, e (2) camundongo geneticamente obeso, ob/ob. A dose e tempo de tratamento escolhidos basearam-se no resultado da tolerância à insulina determinada inicialmente. Os animais receberam via oral o extrato da UT na dose de 50 mg/kg, uma vez ao dia, por 5 dias consecutivos. Seguindo-se ao tratamento, os animais foram submetidos a testes de tolerância a glicose e insulina, análise do coeficiente respiratório e depois a eutanásia, para retirada do fígado e sangue. O tecido hepático foi submetido a técnicas histológicas para verificar a morfologia e quantificação das gotículas de gordura, extração das proteínas celulares e RNAm para realização de western blot típico e reação em cadeia da polimerase (PCR), respectivamente. Também foi utilizada imunohistoquímica com anticorpo anti-F4/80 para comprovar infiltrado inflamatório. O tratamento com UT reduziu a glicemia de jejum cerca de 15 e 20% nos modelos DH e ob/ob, respectivamente, e a insulimenia para 54% no grupo DH, enquanto no grupo ob/ob houve um aumento de 2 vezes na insulinemia com o uso da UT. Houve uma redução de 22% no índice de massa corpórea (IMC) acompanhada de maior gasto energético com o tratamento no modelo DH. A esteatose hepática foi reduzida em aproximadamente 30% e a presença de infiltrados inflamatórios em 70% em ambos os modelos. Além disso, o grau de fosforilação do IRS1 no resíduo serina foi reduzido em 25% nos camundongos alimentados com DH após tratamento com UT, acompanhando a maior sensibilidade à insulina desses animais em relação aos obesos não tratados. Diante desses resultados, concluímos que o extrato bruto da Uncaria tomentosa melhora a homeostase da glicose e reverte a esteatohepatite incipiente a estatose benigna. O tratamento com Uncaria tomentosa pode ser uma estratégia terapêutica potencial no combate a alterações metabólicas associadas à obesidade como a doença hepática gordurosa não alcoólica (DHGNA) de início imediato. / The body\'s energy balance is maintained through changes in calorie intake and energy expenditure. The prolonged positive energy balance, in which the intake exceeds the expense, promotes obesity. Obesity results from the increase of triacylglycerols in adipose tissue, which also starts to present chronic low-grade inflammation. The result of this involves the reduction of the buffering capacity of circulating free fatty acids and subsequent fat deposition in ectopic territories such as skeletal muscle and liver, as well as increasing the risk of developing type 2 diabetes mellitus. Thus, obesity is an important risk factor for metabolic diseases and their comorbidities, among them non-alcoholic fatty liver disease. A therapeutic proposal to intervene in obesity and/or associated comorbidities is the use of substances with anti-inflammatory action. Considering the possibility of new use for some products released for use and with toxic potential already evaluated, it was chosen to evaluate the effect of the herbal remedy Uncaria tomentosa (UT), popularly known as cat\'s claw. Two models of mice were used: (1) higt fat diet induced obesity (HFD), male mice c57bl / 6, fed HFD for 12 weeks, and (2) genetically obese mice, ob/ob. The dose and time of treatment chosen were based on the initially determined insulin tolerance result. The animals received orally the UT extract at the dose of 50 mg/kg once daily for 5 consecutive days. Following the treatment, the animals were submitted to glucose and insulin tolerance tests, analysis of the respiratory coefficient and then euthanasia, for removal of the liver and blood. Liver tissue was submitted to histological techniques to verify the morphology and quantification of fat droplets, extraction of cellular proteins and mRNA for typical western blot and polymerase chain reaction (PCR), respectively. Immunohistochemistry with anti-F4 / 80 antibody was also used to prove inflammatory infiltrate. Treatment with UT reduced fasting glucose by 15 and 20% in the HFD and ob/ob models respectively, and the insukinemia to 54% in the HFD group, whereas in the ob/ob group there was a 2-fold increase in insulinemia with the use of UT. There was a 22% reduction in body mass index (BMI) accompanied by greater energy expenditure with HFD treatment. Hepatic steatosis was reduced by approximately 30% and the presence of inflammatory infiltrates by 70% in both models. In addition, the degree of IRS1 phosphorylation at the serine residue was reduced by 25% in the mice fed HFD after treatment with UT, following the higher insulin sensitivity of these animals compared to the untreated obese. In view of these results, we conclude that the crude extract of Uncaria tomentosa improves glucose homeostasis and reverts incipient steatohepatitis to benign steatosis. Treatment with Uncaria tomentosa can be a potential therapeutic strategy in the action against obesity-related metabolic alterations such as non-alcoholic fatty liver disease (NAFLD).

A influência da obesidade e da resistência à insulina (induzidas em ratos por injeção de glutamato monossódico em neonatos) sobre o desenvolvimento tumoral (5x105 células do tumor de Walker-256) e os efeitos da metformina (300mg/kg, v.o., 15 dias) nessa condição foram investigados. Na 16ª semana de vida, inocularam-se as células e iniciou-se o tratamento. Após 15 dias de tratamento, caracterizou-se a obesidade e a analisou-se o crescimento tumoral. O desenvolvimento tumoral e a caquexia foram maiores nos obesos. A metformina reduziu o desenvolvimento do tumor, mas não a caquexia. Apesar da metformina não ter melhorado a sensibilidade à insulina, corrigiu a dislipidemia, reduziu a peroxidação lipídica e as gorduras periepididimal e retroperitoneal. Conclui-se que a obesidade aumenta o desenvolvimento tumoral e que a metformina é eficaz em diminui-lo. O mecanismo envolvido parece não depender da melhora da sensibilidade à insulina / The influence of obesity and insulin resistance (induced in rats by monosodium glutamate in neonates) on tumor development (5x105 Walker-256 tumor cells) and the effect of metformin (300mg/kg, by gavage, for 15 d) on it. On the 16th week, tumor cells were subcutaneously injected and the treatment started. On the 18th week, the obesity was characterized and the tumor was evaluated. The tumor development and the cachexia were higher in obese rats. The tumor development was reduced by metformin, but not cachexia. Although metformin did not improve insulin sensitivity it did correct the dislypidemia, reduced the periepididimal and retroperitoneal adipose tissues and lipid peroxidation. In conclusion obesity increases tumor development and metformin is able to reduce it. The reduction occurred independently of the correction of insulin resistance

Avaliou-se a participação do óxido nítrico (NO), do fator hiperpolarizante derivado do endotélio (EDHF), dos produtos da ciclooxigenase (COX), das espécies reativas de oxigênio (EROs) e o efeito do tratamento com metformina (Met) nas alterações vasculares em ratos com obesidade induzida por glutamato monossódico (MSG). O tratamento com Met corrigiu alterações metabólicas em ratos MSG, reduzindo o acúmulo de gordura visceral, corrigindo a resistência à insulina, a hiperinsulinemia e a dislipidemia. Ratos MSG apresentaram aumentada resposta contrátil e diminuída sensibilidade à Ach, associadas a alterações na via do NO, do EDHF, dos produtos da COX e das EROs. Ratos MSG com 16 semamas apresentaram hiperresponsividade ao nitroprussiato de sódio, que foi mantida nos ratos tratados com Met. A Met corrige as alterações da resposta vascular atuando sobre o NO e o EDHF, reduzindo a geração de EROs e interferindo na resposta do músculo liso vascular, mantendo a hiperresponsividade ao NO. / The role of the nitric oxide (NO), the endothelium derived hyperpolarizing factor (EDHF), the ciclooxygenase (COX) products and the reactive oxygen species (ROS), as well as the effect of metformin (Met) treatment on the vascular alterations in rat model of obesity induced by monosodium glutamate (MSG) were evaluated. Met treatment corrected metabolic alterations in MSG, reducing fat accumulation, correcting dyslipidemia, insulin resistance and hyperinsulinemia. MSG rats had an increased response to norepinephrine and decreased sensitivity to acetilcholine, which were associated with alterations in NO, COX products and ROS. Sixteen-week-old MSG rats presented hyperresponsiveness to sodium nitroprusside, which was preserved in Met-treated group. Met corrects the alterations of the vascular reactivity acting on NO and EDHF, and decreasing the ROS generation, besides its effect on the vascular smooth muscle response, preserving the hyperresponsiveness to NO.

A síndrome dos ovários policísticos (SOP) constituia causa mais freqüente de infertilidade, anovulação e hiperandrogenismo atualmente. Sua fisiopatogenia é em parte obscura. O hormônio anti-mülleriano (HAM),uma glicoproteína produzida pelas células da granulosa dos folículos pré-antrais e folículos antrais pequenos, parece exercer papel fundamental para seu surgimento, exacerbando o hiperandrogenismo intra-folicular e interferindo no mecanismo de seleção do folículo dominante. Além das alterações ovulatórias, há repercussões metabólicas decorrentes da síndrome, como a resistência à insulina (RI), que afeta entre 45 a 70% das mulheres com SOP em idade reprodutiva. Estratégias para aumentar a sensibilidade à insulina poderiam reduzir o impacto reprodutivo e metabólico da RI. Entre elas, destaca-se a metformina, uma droga anti-diabética oral, cuja utilização levaria a uma melhora dos padrões metabólicos e restabelecimento da ovulação. No presente estudo, foram avaliados a relação entre os níveis séricos de HAM e resistência insulínica antes e após o tratamento com metformina, comparados os níveis séricos de HAM na fase folicular precoce entre pacientes com e sem SOP e correlacionados os níveis de HAM com os níveis séricos de insulina, gonadotrofinas e androgênios. Foram realizadas dosagens séricas de HAM, androgênios e gonadotrofinas em 36 pacientes (16 com SOP e resistência insulínica e 20 eumenorreicas, sendo grupos pareados quanto à idade e índice de massa corpórea). No grupo SOP, foram avaliados níveis de HAM, insulina, glicemia e QUICKI (quantitative insulin check index) antes e depois do tratamento com metformina 1500 mg/dia por oito semanas. Foram encontrados níveis de HAM mais elevados no grupo SOP do que no grupo controle (49,9 ± 6,1 pmol/L versus 4,5 ± 2,1 pmol/L, p < 0,0001), assim como os níveis de hormônio luteinizante (LH) (10,3± 1,5 mUI/L versus 3,5 ±0,5 mUI/L, p=0,0004), testosterona (64,9 ± 5 ng/mL versus 41,1 ±4,7 ng/mL, p=0,0017) e 17-hidroxiprogesterona (17OHP) ( 90 ±16,8ng/ml versus 49,1 ±6,6 ng/ml; p= 0,03). Nas pacientes com SOP, houve correlação positiva forte entre os níveis de HAM pré-tratamento e testosterona (coeficiente r dePearson - R - de 0,83; p<0,0001). Também foi encontrada correlação positiva e significativa entre HAM e LH (R = 0,51; p = 0,04). As demais variáveis não apresentaram correlação significativa com o HAM pré-tratamento. Após o tratamento, houve redução significativa dos níveis de insulina (16,4 ± 2,6 mUI/ml versus 12 ± 1,9 mUI/ml; p=0,0132). Os níveis de HAM tiveram redução, porém sem diferença estatística (49,9 ± 6,1 versus 41,5 ± 5,6 pmol/L; p=0,06). Houve redução significativa nos níveis de testosterona (64,9 ± 5 ng/mL versus 49,3 ± 14 ng/mL). A correlação do HAM com os níveis de testosterona não persistiu após o tratamento com a metformina (R=0,08 e p=0,76). Assim, a manutenção dos níveis séricos de HAM após o uso da metformina, mesmo com a comprovada melhora metabólica e redução dos níveis de gonadototrofinas sugere que o papel do HAM na SOP baseia-se num mecanismo intrínseco ovariano, independente do eixo hipotálmo-hipófise-ovário e não influenciado pela resistência insulínica. / Polycystic ovary syndrome (PCOS) is the most frequent cause of infertility, anovulatory disordes and hyperandrogenism in young women. Its pathophisiology remains unclear and anti-mullerian hormone (AMH), a glycoprotein produced by the granulose cells of early developing follicles, seems to be fundamental to its development, by enhancing the intra-follicular hyperandrogenism and interfering in the selection of a dominant follicle. PCOS also causes metabolic disorders, such as insulin resistance (IR), that affects 45 to 70% of women with PCOS. Strategies to improve insulin sensitivity could reduce the reproductive and metabolic impact of IR.Metformin, a insulin-sensitizing agent, appears to improve the metabolicparameters and reestablish ovulatory cycles. In this study, we evaluated the relationship between anti-mullerian hormone serum levels and IR before and after protracted treatment with meformin; we also compared the anti-mullerian hormone levels in PCOS in the early follicular phase to normo-ovulatory women. The correlation of anti-mullerian hormone levels to insulin, gonatotropins and androgen serum levels was also evaluated. The study included 36 pacients (20 with PCOS and IR and 16 with ovulatory cycles). Anti-mullerian hormone serum levels, insulin, glucose and QUICKI (quantitative insulin check index) were evaluated in patients with PCOS before and after treatment with metformina 1500 mg/day during eight weeks. Anti-mullerian hormone serum levels were higher in PCOS (49,9 ± 6,1 pmol/L versus 4,5 ± 2,1 pmol/L, p < 0,0001), as well as luteinizing hormone (LH) levels (10,3± 1,5 mUI/L versus 3,5 ±0,5 mUI/L, p=0,0004), testosterone (64,9 ± 5 ng/mL versus 41,1 ±4,7 ng/mL, p=0,0017) and 17-ydroxyprogesterone (17OHP) ( 90 ±16,8ng/ml versus 49,1 ±6,6 ng/ml; p= 0,03). In PCOS, there is a positive correlation between anti-mullerian hormoneserum levels and testosterone (R= 0,83; p<0,0001) before treatment; this correlation did not persisted after treatment (R=0,08 e p=0,76). There is also a positive correlation between anti-mullerian hormone serum levels before metformin treatment and LH (R= 0,83; p<0,0001). No correlations were found between anti-mullerian hormone serum levels before treatment and other parameters. After treatment, insulin serum levels reduced (16,4 ± 2,6 mUI/ml versus 12 ± 1,9 mUI/ml; p=0,0132). AMH serum levels also reduced, but therewas no statically significant difference (49,9 ± 6,1 versus 41,5 ± 5,6 pmol/L; p=0,06). Testosterone serum levels decreased significantly (64,9 ± 5 ng/mL versus 49,3 ± 14 ng/mL). No correlation between AMH and testosterone levels was found after treatment (r=0, 08 e p=0, 76). The maintenance of AMH serum levels after treatment with metformin, despite the enhance of metabolic parameters and reduction of the gonadrotopins levels, suggests that AMH acts in the pathophisiology of PCOS by a intra-ovarian mechanism, that does not depend on the neuroendrocine axis and that is not influenced by IR.

A hiperinsulinemia e a resistência à insulina (RI) são descritas em pacientes portadoras da PCOS, independentemente do índice de massa corporal. O exercício físico parece não ser capaz de reverter completamente a RI nessas pacientes, sugerindo uma resposta sub-ótima ao estímulo do treinamento físico nessa população. Assim, o objetivo desse trabalho foi investigar os efeitos agudos do exercício aeróbio sobre a expressão de proteínas envolvidas na sinalização intracelular para captação de glicose em pacientes com PCOS comparadas a mulheres sem comorbidades e sem a PCOS (grupo CTRL). No período basal, as voluntárias realizaram avaliações do perfil lipídico, glicêmico e hormonal, capacidade física e composição corporal. Após a intervenção, as voluntárias realizaram dosagens sanguíneas para a avaliação do perfil inflamatório e glicêmico em resposta ao exercício físico. Além disso, as voluntárias foram submetidas à biopsias musculares, para analises da expressão de proteínas envolvidas na sinalização intracelular para a captação de glicose. A expressão proteica da PI3-k não demonstrou diferenças significantes em resposta à sessão aguda de exercício aeróbio no grupo PCOS. Todavia, o grupo CTRL demonstrou um aumento significante da ativação dessa proteína em resposta à sessão aguda de exercício aeróbio (p = 0.018), bem como uma tendência de diferença significante da atividade dessa proteína na condição PÓS (p = 0.073) no grupo CTRL em comparação ao grupo PCOS. A fosforilação da AS160 Thr 642 foi significante maior no grupo CTRL em resposta a sessão aguda de exercício aeróbio (p = 0.043), enquanto, uma resposta inalterada da fosforilação da AS160 Thr 642 foi observada no grupo PCOS em resposta ao exercício aeróbio agudo. O grupo CTRL apresentou um aumento da fosforilação dessa proteína significante maior que o grupo PCOS na condição PÓS (p = 0.05). Os presentes achados demonstram um prejuízo na sinalização intracelular para captação de glicose no músculo esquelético ao nível da proteína PI3-k p85 e AS160 Thr 642 em resposta ao exercício aeróbio agudo nas mulheres com PCOS comparada as mulheres CTRL. Entretanto, a translocação do GLUT-4 não está prejudicada em resposta ao exercício aeróbio agudo nas mulheres com PCOS comparada as mulheres CTRL. Esses dados sugerem que defeitos de sinalização em proteínas específicas da sinalização insulínica não impedem a efetiva translocação de GLUT-4 no músculo esquelético de pacientes com PCOS / Hyperinsulinemia and insulin resistance (IR) are described in PCOS patients regardless of body mass index. Exercise does not seem to be able to completely reverse the IR in these patients, suggesting a sub-optimal response to the stimulus of exercise training in this population . The objective of this study was to investigate the acute effect of aerobic exercise on the protein expression involved in intracellular signaling for glucose uptake in patients with PCOS compared with women without PCOS (CTRL group). At baseline, subjects underwent assessments of lipid, glucose and hormone profile, physical fitness and body composition. After the intervention, the volunteers performed blood measurements for the assessment of inflammatory markers and glycemic profile in response to acute aerobic exercise. In addition, the volunteers underwent skeletal muscle biopsies for analysis of the protein expression involved in intracellular signaling for glucose uptake. PI3-k expression showed no significant differences in response to acute exercise bout in the PCOS group. However, the CTRL group showed a significant increase in activation of this protein in response to acute exercise bout (p = 0.018) and a trend toward significant difference in activity of this protein after exercise (p = 0.073) in the CTRL group compared to the PCOS group. AS160 Thr 642 phosphorylation was significantly higher in the CTRL group in response to acute exercise bout (p = 0.043), while an unchanged response of AS160 Thr 642 phosphorylation was observed in the PCOS group in response to acute aerobic exercise. CTRL group showed an increase in phosphorylation of this larger than PCOS group significant protein in the period after the acute exercise bout (p = 0.05). The present findings demonstrate a loss in intracellular signaling for glucose uptake in skeletal muscle at the level of the protein PI3 -k p85 and AS160 Thr 642 in response to acute aerobic exercise in women with PCOS compared CTRL women. However, GLUT - 4 translocation is not impaired in response to acute aerobic exercise in women with PCOS compared CTRL women. These data suggest that specific defects of insulin signaling do not impairment the effective GLUT - 4 translocation in skeletal muscle of patients with PCOS, probably by activation of compensatory molecular mechanisms. Keywords: polycystic ovary syndrome, exercise, obesity, insulin